Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DESCRIPTION
METHOD OF MANUFACTURING A MOLDING WITH A CORE
Technical Field
[0001]
The present invention relates to a method of
manufacturing a molding by compression of such a molding
material as powder granule and, more specifically, to a method
of manufacturing a molding with a core by using punches of a
double structure.
Background Art
[0002]
A method of manufacturing a molding by compressing
and solidifying molding material, a representative of which is
powder granule etc., is generally used in a wide range of
industry including, for example, not only industrial fields of
pharmaceuticals and foods (functional foods and general foods)
but also electronic material fields such as molding of
semiconductor encapsulating resin, battery-related products,
powder metallurgy-related products, electronic functional
parts and the like, and fields of agricultural chemicals and
sanitary products.
[0003]
In the field of pharmaceuticals, among formulations
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for oral administration in particular, a solid molding called
"tablet" is presently one of the most widely used form of
medicines in view of various merits including simplicity and
convenience in manufacturing and easiness of oral
administration. Among such moldings, the molding having an
internal core is called "tablet with a core" since such a
molding is manufactured by compression-molding powder granule
placed around a core (center tablet) to form an outer layer.
[0004]
Such a molding with a core as a dry coated tablet
was conventionally manufactured by a method comprising:
preparing a core as a molding by another tablet machine
previously; supplying the core as a molding into a die of a
dry coated tablet machine fed and filled with powder granule
for an outer layer; and further supplying and compression-
molding the powder granule for the outer layer. This
manufacturing method involves serious problems of an increased
amount of operation and a lowered production efficiency as
compared with a method of manufacturing an general compression
molding. Further, the method involves problems associated with
feeding of cores, such as an occurrence of a tablet with no
core, multiple cores, or off-centered core and hence requires
a complicated mechanism or apparatus for monitoring core
feeding and checking final molded products to assure the
quality of each product, thus resulting in the machine or
equipment increased in size and complicated in structure.
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[0005]
In view of such circumstances, the inventors of the
present invention invented a method of manufacturing a molding
with a core efficiently from such a molding material as powder
granule at a time, as described in patent document 1. This
method uses compression molding means having a die and an
upper and a lower punches, of which at least the upper punch,
preferably both of the upper and lower punches have a double
structure comprising a center punch and an outer punch
surrounding the outer periphery of the center punch, both of
the center punch and the outer punch being slidable and
capable of a compressing operation. This manufacturing method
comprises: the steps of supplying molding material for the
core and molding material for the outer layer respectively;
the step of compression-molding the molding material for the
core and/or the molding material for the outer layer; and the
step of compression-molding the whole molding with a core.
[0006]
Further, the inventors of the present invention
invented a rotary compression molding machine described in
patent document 2 as an apparatus for practicing the
aforementioned method of manufacturing a molding with a core.
[0007]
A specific example of such a method of manufacturing
a molding with a core by using upper and lower punches both
having such a double structure comprises: an outer layer
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supply step 1 of supplying molding material for the outer
layer into a space defined above a lower center punch and
enclosed by a lower outer punch; a core supply step of
supplying molding material for the core into a space defined
above the molding material for the outer layer supplied in the
preceding step and enclosed by the lower outer punch; an outer
layer and core molding step of compression-molding the molding
material for the outer layer and the molding material for the
core supplied in the preceding steps; an outer layer supply
step 2 of supplying the molding material for the outer layer
into a space defined above and around the outer layer and core
molding in the die molded in the preceding step; and a whole
molding step of compression-molding the outer layer and core
molding and the molding material for the outer layer.
Patent Document 1: International Laid-Open Publication No. WO
01/98067 pamphlet
Patent Document 2: International Laid-Open Publication No. WO
02/90098 pamphlet
Disclosure of Invention
[0008]
The inventors of the present invention became aware
of the fact that the molding manufactured according to the
aforementioned method of manufacturing a molding with a core
by using the double-structured punches might not have a enough
strength. The inventors investigated the cause of this fact
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and found out the problem regarding the packing density of the
molding material for the outer layer supplied into the space
defined above and around the outer layer and core molding in
the outer layer supply step 2. In other words, the amount of
molding material for the outer layer supplied into the space
around the temporary molding of the outer layer and the core,
that is, the space defined between the outer layer and core
molding and the lower outer punch is equivalent to the
thickness of the temporary molding of the outer layer and the
core and, for this reason, the packing density of the molding
material for the outer layer supplied in this part is
insufficient. It was therefore found out that the strength of
a portion of the outer layer forming the sidewall of the
molding was sometimes insufficient. The present invention has
been made in order to solve this problem.
[0009]
The inventors of the present invention have solved
the aforementioned problem by increasing the amount of the
molding material for the outer layer to be supplied into the
space between the outer layer and core molding and the lower
outer punch in the outer layer supply step 2. Specifically,
the outer layer supply step 2 of supplying the molding
material for the outer layer into the space defined above and
around the aforementioned outer layer and core molding, that
is, the step of supplying the molding material for the outer
layer (the last outer layer supply step) posterior to the
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step of supplying the molding material for the core is
performed until the tip of the lower center punch finally
takes a position protruding from the tip of the lower outer
punch by further lowering the lower outer punch tip, whereby
the packing density of the molding material for the outer
layer forming the sidewall of the molding can be increased and,
hence, the strength of a portion of the outer layer that forms
the sidewall of the molding can be enhanced.
[0010]
Further, surprisingly, a phenomenon has been
observed such that if the outer layer supply step 2 is
performed as described above under certain conditions, the
molding material for the outer layer supplied in the outer
layer supply step 2 is led to under the outer layer and the
core molding during the process of aligning the tips of the
lower center punch and the lower outer punch with each other
to allow the subsequent whole molding step to be performed.
This means that the molding with a core can be prepared even
if the first outer layer supply step 1 is eliminated. Thus, a
novel invention has been completed.
[0011]
That is, the present invention provides a method for
manufacturing a molding with a core by using compression
molding means having an upper punch and a lower punch which
are arranged in the vertical direction of a die, both of the
upper punch and the lower punch having a double structure
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comprising a center punch and an outer punch surrounding the
outer periphery of the center punch, and being slidable and
capable of a compressing operation; the method comprising the
steps of supplying molding material for the core and molding
material for the outer layer respectively, the step of
compression-molding the molding material for the core and/or
the molding material for the outer layer, and the step of
compression-molding the whole molding with a core, wherein:
the step of supplying the molding material includes the step
of supplying the molding material for the core and the
subsequent step of supplying the molding material for the
outer layer; the step of supplying the molding material for
the outer layer is performed until a tip of the lower center
punch finally takes a position protruding from a tip of the
lower outer punch; and the step of compression-molding the
whole molding with a core is performed with the tips of the
lower center punch and the lower outer punch aligned with each
other.
[0012]
In this method, the step of supplying the molding
material for the outer layer can be performed prior to the
step of supplying the molding material for the core as in the
conventional art. In this case, the step of supplying the
molding material usually consists of the three steps: the
first step of supplying the molding material for the outer
layer; the subsequent step of supplying the molding material
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for the core; and the second subsequent step of supplying the
molding material for the outer layer.
[0013]
According to the present invention, a molding with a
core can be manufactured without performing the step of
supplying the molding material for the outer layer prior to
the step of supplying the molding material for the core. In
this case, the step of supplying the molding material usually
consists of the two steps: the step of supplying the molding
material for the core; and the subsequent step of supplying
the molding material for the outer layer.
[0014]
An essential feature of the present invention is
that the step of supplying the molding material for the outer
layer, which follows the step of supplying the molding
material for the core, is performed until the tip of the lower
center punch finally takes a position protruding from the tip
of the lower outer punch, and then the step of compression-
molding the whole molding is performed with the tips of the
lower center punch and the lower outer punch aligned with each
other. This feature gives rise to the effect of enhancing the
strength of the sidewall of the molding and/or the effect of
allowing the manufacture of a molding with a core to be
achieved through the step of supplying molding material
performed twice.
[0015]
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In a case of the present invention, it is possible
to obtain a molding with a core having a enhanced and
sufficient strength in a portion of the outer layer forming
the sidewall thereof when the molding with a core is
manufactured by the method using compression molding means
having an upper and a lower punch and a die, both of the upper
punch and the lower punch having a double structure comprising
a center punch and an outer punch surrounding the outer
periphery of the center punch, and being slidable and capable
of a compressing operation. In another case of the present
invention, it is possible to eliminate the outer layer supply
step 1 preceding the step of supplying the molding material
for the core, because the last supplied molding material for
the outer layer is led to under the outer layer and core
molding. Hence, the molding with a core can be manufactured
through the step of supplying molding material performed twice.
In the method of manufacturing a molding with a core through
the step of supplying molding material performed twice, it is
possible to manufacture a molding with a core while enhancing
the strength of a portion of the outer layer forming the
sidewall of the molding. Further in another case of the
present invention, the aforementioned phenomenon that the
molding material for the outer layer is led to under the outer
layer and core molding provides no boundary between a portion
of outer layer forming the bottom of the molding and a portion
of outer layer forming the sidewall of the molding, thus
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making it possible to prevent contamination of the molding
material for the core which would otherwise occur frequently
in the conventional manufacturing method on the bottom surface
of the molding due to the provisionally molded core shaved
during the preparation process.
Brief Description of Drawings
[0016]
[FIG. 1] Fig. 1 is an explanatory view illustrating movement
of punch tips in a first mode for carrying out the method of
manufacturing a molding with a core according to the present
invention. (Hatching representing a section is omitted for
convenience.)
[FIG. 2] Fig. 2 is an explanatory view illustrating movement
of punch tips in a second mode for carrying out the method of
manufacturing a molding with a core according to the present
invention. (Hatching representing a section is omitted for
convenience.)
[FIG. 3] Fig. 3 is an explanatory view illustrating movement
of punch tips in a third mode for carrying out the method of
manufacturing a molding with a core according to the present
invention. (Hatching representing a section is omitted for
convenience.)
[FIG. 4] FIG. 4 is a photograph illustrating movement of
punch tips in example 3 of the method of manufacturing a
molding with a core according to the present invention.
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[FIG. 5] FIG. 5 is a photograph illustrating movement of punch tips in example
4 of the method
of manufacturing a molding with a core according to the present invention.
[FIG. 6] FIG. 6 is a table illustrating the effect of varying amounts of
descent of a lower outer
punch on the condition of the reverse side of a tablet.
Description of reference characters
[0017]
3 : die
4A : upper center punch
4B: upper outer punch
5A: lower center punch
513: lower outer punch
NP : molding material for the core
OP1 first molding material for the outer layer
OP2 : second molding material for the outer layer
Best Mode for Carrying Out the Invention
[0018] The term "molding material", as used in the present specification, is
meant to include all
moldable material including both wet and dry material such as powder granule
etc. The term
"powder granule" is used to represent any one of material including all of
powder, granule/pellet
and analog thereof. Preferably, powder granule is used as the molding
material.
[0019] The method of the present invention is an improved
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invention of the method described in patent document 1.
Specifically, the invention described in patent document 1 is
a method of manufacturing a molding with a core by using
compression molding means having an upper punch and a lower
punch in the vertical direction of a die, both of the upper
punch and the lower punch having a double structure comprising
a center punch and an outer punch surrounding the outer
periphery of the center punch, and being slidable and capable
of a compressing operation, the method comprising: an outer
layer supply step 1 of supplying molding material for the
outer layer into a space defined above a lower center punch
and enclosed by a lower outer punch; a core supply step of
supplying a molding material for the core into a space defined
above the molding material for the outer layer supplied in the
preceding step and enclosed by the lower outer punch; an outer
layer and a core molding step of compression-molding the
molding material for the outer layer and molding material for
the core supplied in the preceding steps; an outer layer
supply step 2 of supplying the molding material for the outer
layer into a space defined above and around the outer layer
and core molding in the die which has been molded in the
preceding step; and an whole molding step of compression-
molding the outer layer and core molding and the molding
material for the outer layer
[0020]
According to the method of the present invention,
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the outer layer supply step 2 is performed until a tip of the
lower center punch finally takes a position protruding from a
tip of the lower outer punch and then the whole molding step
is performed with the tips of the lower center punch and the
lower outer punch aligned with each other in the method
described in patent document 1. By so doing, it is possible
to eliminate the outer layer supply step 1. Specifically, the
method of the present invention can be expressed as follows.
[0021]
A method for manufacturing a molding with a core by
using compression molding means having an upper punch and a
lower punch which are arranged in the vertical direction of a
die, both of the upper punch and the lower punch having a
double structure comprising a center punch and an outer punch
surrounding the outer periphery of the center punch, and being
slidable and capable of a compressing operation; the method
comprising a core supply step of supplying molding material
for the core into a space defined above the lower center punch
and enclosed by the lower outer punch, a core molding step of
compression-molding the molding material for the core supplied
in the preceding step; an outer layer supply step of supplying
molding material for the outer layer into a space defined
above and around the molding in the die which has been molded
in the preceding step until a tip of the lower center punch
finally takes a position protruding from a tip of the lower
outer punch; and a whole molding step of compression-molding
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the core molding and the molding material for the outer layer
with the tips of the lower outer punch and the lower center
punch aligned with each other.
[0022]
This method may include an outer layer supply step
of supplying the molding material for the outer layer in the
space defined above the lower center punch and enclosed by the
lower outer punch prior to the core supply step like the
conventional method. If this outer layer supply step is
performed, it is preferable to perform an outer layer molding
step of compression-molding the molding material for the outer
layer after the outer layer supply step. In any case, the
compression molding step other than the whole molding step are
preferably performed as temporary compression. The expression
"the whole molding step is performed with the tips of the
lower center punch and the lower outer punch aligned with each
other", as used herein, is meant to include the case where the
whole molding step is performed after the tips of the lower
center punch and the lower outer punch have been aligned with
each other and the case where the whole molding step is
performed while aligning the tips of the lower center punch
and the lower outer punch with each other.
[0023]
In the outer layer supply step of supplying the
molding material for the outer layer until the tip of the
lower center punch finally takes a position protruding from
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the tip of the lower outer punch, the amount of protrusion of
the tip of the lower center punch from the tip of the lower
outer punch, that is, the amount of descent of the tip of the
lower outer punch relative to the tip of the lower center
punch has preferable ranges to meet respective purposes.
[0024]
When the effect of enhancing the strength of a
portion of outer layer forming the sidewall of the molding
(hereinafter will be referred to as the effect of filling with
a high-density outer layer) is desired, the amount of descent
of the tip of the lower outer punch must not be too much.
This is because if the tip of the lower center punch protrudes
too much from the tip of the lower outer punch, stated
otherwise, if the tip of the lower outer punch is lowered too
much relative to the tip of the lower center punch, a
resulting excessive rise in the density of the outer layer
forming the sidewall of the molding gives rise to a density
difference between the core portion and the outer layer
portion, thus causes deterioration of the formability of the
whole molding. For this reason, it is preferable to supply
the molding material for the outer layer with the amount of
protrusion of the tip of the lower center punch or the amount
of descent of the tip of the lower outer punch adjusted so as
not to produce a large difference of the powder layer density
between the core portion and the outer layer portion of the
molding with a core after the whole molding step. The optimum
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amount of descent of the tip of the lower outer punch cannot
be determined unconditionally because the optimum amount of
descent varies depending upon various conditions including the
shape and size of the temporary molding, the thickness of the
outer layer, and the density of the temporary molding.
However, in the manufacture of a common tablet with a core,
the amount of descent of the tip of the lower outer punch is
preferably about 2 to 0.5 times as much as the thickness of
the molding including a core that has been temporarily molded
before this step.
[0025]
When the effect of allowing the manufacture of a
molding with a core to be achieved through the molding
material supply step performed twice (hereinafter will be
referred to as the effect of leading an outer layer) is
desired, a sufficient amount of descent of the tip of the
lower outer punch to a certain degree is needed so as to allow
the molding material for the outer layer to be led to under
the temporary molding of the core. Though the "sufficient
amount of descent of the tip of the lower outer punch to a
certain degree", as used herein, cannot be determined
unconditionally because the sufficient amount of descent
varies depending upon various conditions including the shape
and size of the temporary molding, the thickness of the outer
layer, and the density of the temporary molding. However, in
the manufacture of a common tablet with a core, the sufficient
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amount of descent is preferably about 0.5 to 8 times as much
as the thickness of the temporary molding containing a core
that has been temporarily molded before this step.
[0026]
After the tip of the lower center punch has finally
taken the position protruding from the tip of the lower outer
punch in the outer layer supply step, the process of aligning
the tips of the lower center punch and the lower outer punch
with each other for the subsequent whole molding step can be
achieved by raising the lower outer punch or lowering the
lower center punch, or lowering the lower center punch while
raising the lower outer punch. Which of these options to be
selected is determined depending upon the purpose to a certain
degree. Namely, it is basically advantageous that: the method
to raise the lower outer punch is selected when the effect of
filling with a high-density outer layer is desired; the method
to lower the lower center punch is selected when the effect of
leading an outer layer is desired; and the method to lower the
lower center punch while raising the lower outer punch is
selected when both of the effects are desired.
[0027]
In any selected method, the condition of the upper
punch is an important factor in attaining the purpose. Namely,
in the case of the method to raise the lower outer punch, the
effect of filling with a high-density outer layer can be
accomplished sufficiently by performing the operation of
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aligning the tips of the lower center punch and the lower
outer punch with each other from the position in which the tip
of the lower center punch is protruded from the tip of the
lower outer punch with the upper center punch and upper outer
punch pressing the molding material in the die. In the case
of the method to raise the lower outer punch, the effect of
leading an outer layer can be expected by performing the
operation of aligning the tips of the lower center punch and
the lower outer punch with each other from the position in
which the tip of the lower center punch is protruded from the
tip of the lower outer punch with the upper center punch and
upper outer punch not pressing the molding material in the die.
[0028]
On the other hand, in the case of the method to
lower the lower outer punch, the effect of leading an outer
layer can be accomplished sufficiently by performing the
process of pressing the molding material in the die by the
upper center punch and the upper outer punch in the position
in which the tip of the lower center punch is protruded from
the tip of the lower outer punch. And in the case of the
method to lower the lower center punch while raising the lower
outer punch, both of the effects can be accomplished
sufficiently by performing the operation of aligning the tips
of the lower center punch and the lower outer punch with each
other from the position in which the tip of the lower center
punch is protruded from the tip of the lower outer punch with
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the upper center punch and upper outer punch pressing the
molding material in the die.
[0029]
After all, the present invention generally performs
the process of pressing the molding material in the die by the
upper center punch and the upper outer punch during the
operation of aligning the tips of the lower center punch and
the lower outer punch with each other from the position in
which the tip of the lower center punch is protruded from the
tip of the lower outer punch. Note that the expression
"pressing the molding material in the die by the upper center
punch and the upper outer punch", as used herein, means light
pressurization to such an extent that the upper center punch
and upper outer punch covering the molding material in the die
press the molding material by their own weights or to such an
extent as to press the molding material in the die by lowering
the upper punch along the rail of the upper punch, unlike a
common compression molding process using a compression roll.
Though not preferable, the molding material may be pressed by
using an ordinary compression roll.
[0030]
Even in the method of the present invention, the
step of removing residual molding material remaining on the
lower outer punch is necessary to be performed or preferable
to be performed depending on the punch tip shape. Refer to
patent document 1 with respect to the details of such cases.
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[0031]
Hereinafter, a first mode for carrying out the
method of manufacturing a molding with a core according to the
present invention will be described in detail with main
reference to FIG. 1.
[0032]
Initially, with the lower center punch 5A in a
lowered position (FIG. 1A), molding material for the first
outer layer OP1 is supplied into the first outer layer space
201A defined above the lower center punch 5A and enclosed by
the lower outer punch 5B (FIG. 1B). When required, the lower
center punch 5A is raised to discharge excess of the first
molding material for the outer layer out of the die.
Thereafter, the upper center punch 4A and the lower center
punch 5A are moved toward each other and pressed temporarily
(FIG. 1C) to mold the first outer layer.
[0033]
Subsequently, with the temporary molding of the
first outer layer OP1 held by the lower center punch 5A and
the lower outer punch 5B, molding material for the core NP is
supplied into the core space 202A defined above the temporary
molding of the first outer layer OP1 and enclosed by the lower
outer punch 5B (FIGs. lE and 1F). Thereafter, the lower
center punch 5A is raised to discharge excess of the molding
material for the core out of the die when required, and then
the upper center punch 4A and the lower center punch 5A are
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moved toward each other and pressed temporarily (FIG. 1G) to
mold the first outer layer temporary molding and the core.
[0034]
Further, with the temporary molding of the first
outer layer and the core held on the lower center punch 5A,
molding material for the second outer layer OP2 is supplied
into the second outer layer space 203A defined above and
around the temporary molding of the first outer layer and the
core in the die 3 (FIGs. 1J and 1K) until the tip of the lower
center punch takes a position properly protruding from the tip
of the lower outer punch by lowering the lower punch (both of
the lower center punch 5A and the lower outer punch 5B or the
lower outer punch 5B alone) (FIG. 1I) and then further
lowering the lower outer punch 5B. With the temporary molding
of the core held on the temporary molding of the first outer
layer being completely covered by the molding material for the
outer layer and the temporary molding of the outer layer,
excess of the molding material for the second outer layer OP2
is discharged out of the die when required (FIG. 1K). Here,
it is possible to supply the molding material for the second
outer layer OP2 after the lower outer punch 5B has been
previously lowered sufficiently to protrude the lower center
punch tip from the lower outer punch tip. Thereafter, with
the upper center punch and upper outer punch pressing the
molding material in the die, the lower outer punch tip is
raised to align with the lower center punch tip (FIGs. 1L and
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1M). Then, the upper punch (upper center punch 4A and upper
outer punch 4B) and the lower punch (lower center punch 5A and
lower outer punch 5B) are moved toward each other to perform
main compression finally on the whole molding consisting of
the first outer layer, the core, and the second outer layer
(FIG. 1M), optionally with pre-compression (temporary
compression) when required. FIG. 1N illustrates the step of
taking out the completed molding.
[0035]
The step of removing residual molding material 57
(57A and 57B) remaining on the lower outer punch 7B (FIGs. 1D
and 1H) is preferably added, depending on the shape of the tip
portion (depicted at 7B in FIG. 1) of the outer punch, after
supply of the first outer layer OP1 or during compression
molding or after compression molding thereof and after supply
of the core NP or during compression molding or after
compression molding thereof in order to prevent contamination
of the molding material for the outer layer and the molding
material for the core. With respect to the details of this
removal step, refer to patent document 1 again.
[0036]
Next, a second mode for carrying out the method of
manufacturing a molding with a core according to the present
invention will be described in detail with main reference to
FIG. 2.
[0037]
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Initially, with the lower center punch 5A in a
lowered position (FIG. 2A), molding material for the core NP
is supplied into the core space 302A defined above the lower
center punch 5A and enclosed by the lower outer punch 5B (FIG.
2B). When required, the lower center punch 5A is raised to
discharge excess of the core NP molding material out of the
die. Thereafter, the upper center punch 4A and the lower
center punch 5A are moved toward each other and pressed
temporarily (FIG. 2C) to mold the core.
[0038]
Subsequently, with the temporary molding of the core
held on the lower center punch 5A, molding material for the
outer layer OP2 is supplied into the outer layer space 303A
defined above and around the temporary molding of the core in
the die 3 until the lower center punch tip takes a position
properly protruding from the lower outer punch tip by lowering
the lower punch (both of the lower center punch 5A and the
lower outer punch 5B or the lower outer punch 5B alone)(FIG.
2E) and then further lowering the lower outer punch 5B(FIG.
2F). When required, excess of the molding material for the
outer layer OP2 is discharged out of the die (FIG. 2G) . Here,
it is possible to supply the molding material for the outer
layer OP2 after the lower outer punch 5B has been previously
lowered sufficiently to protrude the lower center punch tip
from the lower outer punch tip. Thereafter, with the lower
center punch tip in the position protruding from the lower
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outer punch tip, the molding material in the die is lightly
pressed by the upper center punch and the upper outer punch
and then the lower center punch tip is lowered to form the
space 304A between the temporary molding of the core and the
lower center punch, thus allowing the molding material for the
outer layer OP2 to be led to fill the space 304A (FIGs. 2H to
2J). With the lower center punch tip and the lower outer
punch tip thus aligned with each other finally, the upper
punch (upper center punch 4A and upper outer punch 4B) and the
lower punch (lower center punch 5A and lower outer punch 5B)
are moved toward each other to perform main compression
finally on the whole molding consisting of the core and the
outer layer (FIG. 2K), optionally with pre-compression
(temporary compression) when required. FIG. 2L illustrates
the step of taking out the completed molding.
[0039]
Next, a third mode for carrying out the method of
manufacturing a molding with a core according to the present
invention will be described in detail with main reference to
FIG. 3.
[0040]
Initially, with the lower center punch 5A in a
lowered position (FIG. 3A), molding material for the core NP
is supplied into the core space 402A defined above the lower
center punch 5A and enclosed by the lower outer punch 5B (FIG.
3B). When required, the lower center punch 5A is raised to
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discharge excess of the core NP molding material out of the
die. Thereafter, the upper center punch 4A and the lower
center punch 5A are moved toward each other and pressed
temporarily (FIG. 3C) to mold the core.
[0041]
Subsequently, with the temporary molding of core
held on the lower center punch 5A, molding material for the
outer layer OP2 is supplied into the outer layer space 403A
defined above and around the temporary molding of the core in
the die 3 until the lower center punch tip takes a position
properly protruding from the lower outer punch tip by lowering
the lower punch (both of the lower center punch 5A and the
lower outer punch 5B or the lower outer punch 5B alone)(FIG.
3E) and then further lowering the lower outer punch 5B(FIG.
3F). When required, excess of the molding material for the
outer layer OP2 is discharged out of the die (FIG. 3G) . Here,
it is possible to supply the molding material for the outer
layer OP2 after the lower outer punch 5B has been previously
lowered sufficiently to protrude the lower center punch tip
from the lower outer punch tip. Thereafter, with the lower
center punch tip in the position protruding from the lower
outer punch tip and with the molding material in the die
lightly pressed by the upper center punch and upper outer
punch, the lower center punch 5B is lowered while the lower
outer punch 5B is raised (FIG. 3H). By so doing, the molding
material for the outer layer OP2 is allowed to be led to the
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26
space formed by lowering the lower center punch while
increasing the density of the outer layer OP2 molding material
on the lower outer punch, namely, the density of the sidewall
of the molding. Thus, the core is completely covered by the
molding material for the outer layer OP2 (FIG. 3I). With the
lower center punch tip and the lower outer punch tip thus
aligned with each other finally, the upper punch (upper center
punch 4A and upper outer punch 4B) and the lower punch (lower
center punch 5A and lower outer punch 5B) are moved toward
each other to perform main compression finally on the whole
molding consisting of the core and the outer layer (FIG. 3J),
optionally with pre-compression (temporary compression) when
required. FIG. 3K illustrates the step of taking out the
completed molding.
[0042]
Next, a fourth mode for carrying out the method of
manufacturing a molding with a core according to the present
invention will be described in detail with main reference to
FIG. 3.again.
[0043]
The manufacturing method according to this mode is
basically the same as the manufacturing method according to
the foregoing mode (third mode) but is different therefrom in
that the lower outer punch 5B is raised from the position in
which the lower center punch tip is protruded from the lower
outer punch tip (FIG. 3G) until the lower outer punch tip and
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the lower center punch tip become aligned with each other
(FIGs. 3H and 3J) without the upper outer punch 4A and upper
center punch 4B lightly pressing the molding material in the
die. As a result, the molding material for the outer layer
OP2 is allowed to be led into the space formed between the
temporary molding of the core and the lower center punch 5A,
thus completely covering the core. Other steps are the same
as in the third mode.
[0044]
In these modes, there are some preferable conditions
for allowing the molding material for outer layer OP2 to be
led to between the temporary molding of the core and the lower
center punch. The following description is directed to these
conditions.
[0045]
First, the punch tip shape of the double-structured
punch is preferably not a flat shape. A punch tip of a flat
shape is such that when the lower center punch tip and the
lower outer punch tip become aligned with each other in the
step of compression-molding the whole molding (main
compression) according to the method of the present invention,
the two punch tips lie on the same level to form one plane. A
punch of the double structure having an unflat punch tip shape
is a punch which has a punch tip having an bevel edge surface
such that the outer periphery of the lower outer punch rises
at an acute angle from the tip end surface of the center punch
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or a curved surface or the like formed when the lower center
punch tip and the lower outer punch tip become aligned with
each other. In such a punch of the double structure having an
bevel edge surface or a curved surface, the molding material
for outer layer OP2 is allowed to be led more suitably as the
difference in level between the endmost portion of the lower
outer punch tip and the most depressed portion of the lower
center punch tip at the time the lower center punch tip and
the lower outer punch tip become aligned with each other
becomes larger.
[0046]
In relation to the amount of the molding material
for outer layer 0P2 to be supplied into the die until the
lower center punch tip takes the position protruding from the
lower outer punch tip, the preferable amount of the molding
material supplied slightly depends upon how the punches slide,
that is, to raise the lower outer punch or to lower the lower
center punch in the process of aligning the lower center punch
tip and the lower outer punch tip with each other. For
example, in case the lower outer punch is to be raised, the
amount of the molding material for the outer layer to be
supplied on the upper surface of the temporary molding of the
core is preferably an adequate amount. The "adequate amount",
as used herein, is such an amount of the outer layer OP2
molding material as to allow the temporary molding of the core
to rise toward the upper punch with the lower outer punch tip
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29
rising from the position in which the lower center punch tip
is protruded from the lower outer punch tip. On the other
hand, in case the lower center punch is to be lowered, the
amount of the molding material for the outer layer to be
supplied into the space formed by lowering the lower outer
punch tip than the lower center punch tip is preferably an
adequate amount. The "adequate amount", as used herein, is
such an amount of the outer layer that during the final
compression (whole compression) the molding material for the
outer layer is allowed to be led with collapsing into the
space formed above the lower center punch by lowering the
lower center punch after pressing the molding material in the
die by the upper punch with the lower center punch tip in the
position protruding from the lower outer punch tip, thereby
completely covering the core, as described above.
[0047]
Thus allowing the molding material for the outer
layer to be led to fill the space between the temporary
molding of the core and the lower center punch leads to
prevention of contamination with the molding material for the
core which is likely to occur on a bottom surface portion of
the final molding corresponding to the contour of the center
punch. The contamination with the molding material for the
core, which is often observed in the conventional method, is
caused by a small portion of the temporary molding of the core
that is shaved off due to contact with an inner portion of the
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tip end of the lower outer punch, adheres thereto and remains
on the final molding during the process of pressing up the
temporary molding of the core and the outer layer into the
molding material for the second outer layer in the die. On
the other hand, in the method of the present invention, it is
considered that as the molding material for the outer layer is
allowed to be led to under the molding of the outer layer and
the core and to cover the contaminated portion with pressing
the portion toward the temporary molding of the core, such
contamination can be reduced or prevented.
[0048]
The method of manufacturing a molding with a core
according to the present invention can be practiced by using
compression molding means having upper and lower punches which
are arranged in the vertical direction of a die, both of the
upper punch and the lower punch having a double structure
comprising a center punch and an outer punch surrounding the
outer periphery of the center punch and being slidable and
capable of a compressing operation (see patent document 1). An
example of such compression molding means is a rotary
compression molding machine described in patent document 2.
Basically, the method of the present invention can be
practiced easily by means of a hydraulic press provided with
upper and lower punches of the double structure and a die.
That is, the method of the present invention can be practiced
easily by performing a series of steps according to the order
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of steps of the present invention, comprising: moving the upper and lower
punches or center and outer punches to respective predetermined positions
manually and/or automatically; supplying the intended molding material
(molding material for the outer layer and molding material for the core); and
compressing the molding material from above and below by means of the
hydraulic press.
[0049]
Example 1
Hereinafter, examples of the present invention will be described
including: example 1 in which the formability of a molding with a core was
improved by improving the packing density of the molding material for the
outer layer; and examples 2 to 4 as manufacture examples of a molding with
a core in each of which the molding material for the outer layer was supplied
and led.
[Manufacture example 1]
A small amount of magnesium stearate (produced by TAIHEI CHEMICAL
INDUSTRIAL CO., LTD.) was applied to the surfaces of respective of upper and
lower punches each of which had a double structure with an inner diameter of
mm , an outer diameter of 8 mm and a flat bevel and was capable of
pressing. With the lower center punch in a lowered position, 30 mg of a spray-
dried product of lactose-crystalline cellulose ("MicrocellacTM" produced by
MEGGLE hereinafter will be referred to as molding material A) was supplied
into the
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space defined above the lower center punch and enclosed by the
lower outer punch. The upper center punch and the lower
center punch were then moved toward each other and temporary
compression was performed manually on the molding material A
to such an extent as to flatten the surface of the molding
material A, thus giving a temporary molding of the first outer
layer. Subsequently, with the lower center punch in a lowered
position, 100 mg of mixed powder consisting of acetaminophene
("ACETAMINOPHENE" produced by Tyco Healthcare Co.) and the
molding material A in proportions of 1:3 was supplied into the
space defined above the temporary molding of the molding
material A previously supplied and enclosed by the lower outer
punch. The upper center punch and the lower center punch were
then moved toward each other and temporary compression was
performed at a compressive pressure of 0.3 kN by means of a
universal tension and compression tester ("AG-I 20kN"
manufactured by Shimadzu Corporation.), to give a temporary
molding of the core. Finally, the lower punch was lowered and
further the lower outer punch was lowered to take a position
in which the tip end portion of the lower outer punch was
lower than the tip end portion of the lower center punch by 3
mm (about 0.7 times as large as the thickness of the temporary
molding of the outer layer and the core) . With the lower
punch in this condition, 260 mg of remaining molding material
A was supplied into a space defined above and around the
temporary molding consisting of the aforementioned outer layer
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and the core in the die to cover the temporary molding of the
core with molding material A completely. With the upper punch
pressing molding material A in the die, the lower outer punch
was raised manually until its punch tip aligned with the lower
center punch tip. The upper punch and the lower punch were
then moved toward each other and tableting was performed at a
compressive pressure of 7.5 kN by means of the aforementioned
universal tension and compression tester. The weight of the
obtained tablet was 390 mg per tablet.
[Comparative manufacture example 1]
A tablet was prepared under the same conditions as
in the manufacture example 1 except that the supply of molding
material A to cover the temporary molding of the core in the
manufacture example 1 was performed with the punch tip end
portions of the lower outer punch and the lower center punch
aligned with each other (with the amount of descent set to 0
mm). The weight of the obtained tablet was 390 mg per tablet.
[Experimental example 1]
(a) Evaluation of tablet hardness
The tablet hardness of each of the tablets obtained
by manufacture example 1 and comparative manufacture example 1
was evaluated by measuring the maximum stress at destruction
on each of the tablets pressed diametrically by means of a
rheometer (manufactured by SUN SCIENTIFIC CO., LTD.). The
results were as shown in Table 1.
(b) Evaluation of friability
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The friability of each of the tablets obtained by
manufacture example 1 and comparative manufacture example 1
was evaluated by using a motor-driven drum (ELECTROLAB:EF1-W)
according to a test method of determining the friability test
of tablet (equivalent to USP24 General/information <1216>
TABLET FRIABILITY) as reference information in Japanese
Pharmacopoeia, 13th revision, second addenda. The results were
as shown in Table 1.
[0050]
[Table 1]
EVALUATION COMPARATIVE MANUFACTURE MANUFACTURE EXAMPLE 1
ITEM EXAMPLE 1 AMOUNT OF DESCENT OF
AMOUNT OF DESCENT OF THE THE LOWER OUTER PUNCH
LOWER OUTER PUNCH 0 mm 3 mm
TABLET
HARDNESS 61.7 - 52.ON 82.4 - 72.ON
(MEAN VALUE) (58.ON) (78.3N)
TABLET
FRIABILITY
1.49% 1.09%
[0051]
As can be seen from table 1, manufacture example 1
in which the amount of descent of the lower outer punch was 3
mm was superior in both of tablet hardness and friability to
comparative manufacture example 1 in which the amount of
descent of the lower outer punch was 0 mm. From these results,
it was concluded that the tablet manufactured with the amount
of descent of the lower outer punch set to 3 mm had an
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improved packing density of outer layer and hence, improved
formability as compared with the tablet manufactured with the
amount of descent of the lower outer punch set to 0 mm.
[0052]
Example 2
[Manufacture example 2]
A small amount of magnesium stearate was applied to
the surfaces of respective of upper and lower punches each of
which had a double structure with an inner diameter of 7 mmO,
an outer diameter of 8 mm and a flat bevel and was capable of
pressing. With the lower center punch in a lowered position,
100 mg of a spray-dried product of lactose-crystalline
cellulose (molding material A) for the core was supplied into
the space defined above the lower center punch and enclosed by
the lower outer punch. The upper center punch and the lower
center punch were then moved toward each other and temporary
compression of the core was performed at a compressive
pressure of 1 kN by means of the universal tension and
compression tester ("AG-I 20kN" manufactured by Shimadzu
Corporation) . Subsequently, the lower outer punch was lowered
to take a position in which the tip end portion of the lower
outer punch was lower than the tip end portion of the lower
center punch by 1, 2 or 3 mm. With the lower punch in this
condition, 130 mg of remaining molding material that was
colored with Food Red No. 3 dye (produced by FFI Corporation)
was supplied into the space defined above and around the
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temporary molding of the core. With the upper punch pressing the molding
material
A in the die, the lower center punch was lowered manually until its punch tip
aligned with the lower outer punch tip. The upper punch and the lower punch
were
then moved toward each other and tableting was performed at a compressive
pressure of 5 kN by means of the aforementioned universal tension and
compression tester. The weight of the obtained tablet was 230 mg per tablet.
[Comparative manufacture example 2]
A tablet was manufactured under the same conditions as in the manufacture
example 2 except that the supply of colored molding material A in the
manufacture
example 2 was performed with the tip end portions of the lower outer punch and
the lower center punch aligned with each other (with the amount of descent set
to
0 mm). The weight of the obtained tablet was 230 mg per tablet.
[Test example 2]
(a) Evaluation of the effect of leading molding material
The bottom surface of each of the tablets of manufacture example 2 and
comparative manufacture example 2 was observed to evaluate the colored outer
layer being led to under the core layer.
CA 02544526 2011-05-16
37
[0054]
As can be seen from Figure 6, the amount of the molding material for the
outer layer to be led to under the bottom portion of the temporary molding of
the
core was observed to increase with increasing amount of descent of the lower
outer
punch in the manufacture example 2 and it was certain that the amount of
descent
of the lower outer punch set to 3 mm (the same as the thickness of the
temporary
molding of the core) allowed the molding material to cover the molding of the
core
completely. As can be understood from these results, by performing the step of
supplying the molding material for the outer layer with the lower outer punch
tip
positioned lower than the lower center punch tip to allow the molding material
to be
led to under the temporary molding of the core, a molding with a core can be
manufactured through only two molding material supply steps, i.e., the step of
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supplying the molding material for the core and the subsequent
step of supplying the molding material for the outer layer.
[0055]
Example 3
[Manufacture example 3]
Description will be made of manufacture example 3 in
accordance with the flow shown in FIG. 4. Upper and lower
punches each of which had a double structure with an inner
diameter of 6 mm o, an outer diameter of 8 mm o and a flat
bevel and was capable of pressing were each sectioned along
the direction of compression, and reinforced glass was fitted
on a die which was sectioned to allow the condition of powder
under compression to be observed visually. Further, a small
amount of magnesium stearate was applied to the each surface
of the punches and the die. With the lower center punch in a
lowered position, a spray-dried product of lactose-crystalline
cellulose (molding material A) that was colored with Food Red
No. 3 dye was supplied into the space defined above the lower
center punch and enclosed by the lower outer punch. The upper
center punch and the lower center punch were then moved toward
each other and temporary compression was performed manually to
such an extent as to flatten the surface of the molding
material A, thus giving a temporary molding of the core (FIGs.
4c and 4d). Subsequently, the lower punch was lowered and
further the lower outer punch was lowered to a position in
which the lower center punch was protruded by about 3 mm from
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the lower outer punch. With the lower punch in this condition,
the uncolored molding material A was supplied into the space
defined above and around the temporary molding of the core in
the die. With the lower punch kept in the aforementioned
condition, the temporary molding of the core and the uncolored
molding material A in the die were pressed manually (FIG. 4f).
Thereafter, the lower center punch was lowered manually until
its punch tip aligned with the lower outer punch tip (FIG. 4g)
to form a space between the colored temporary molding of the
core and the lower center punch for the molding material A to
be led into the space (FIG. 4h). Further, the upper punch and
the lower punch were moved toward each other and manual
compression was performed to allow the uncolored molding
material A to be led with collapsing into this space. In this
way, it was possible to manufacture a tablet with a core by
performing the supply of powder only twice. FIG. 4i shows a
tablet with a core in a condition ready to be taken out.
[0056]
Example 4
[Manufacture example 4]
Description will be made of manufacture example 4 in
accordance with the flow shown in FIG. S. The punches and die
used in this example were the same as in example 3. With the
lower center punch in a lowered position, a spray-dried
product of lactose-crystalline cellulose (molding material A)
that was colored with Food Red No. 3 dye was supplied into the
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space defined above the lower center punch and enclosed by the
lower outer punch. The upper center punch and the lower
center punch were then moved toward each other and temporary
compression was performed manually to such an extent as to
flatten the surface of the molding material A, thus giving a
temporary molding of the core (FIG. 5C) . Subsequently, the
lower punch was lowered and further the lower outer punch was
lowered to a position in which the lower center punch was
protruded by about 3 mm from the lower outer punch. With the
lower punch in this condition, the uncolored molding material
A was supplied into the space defined above and around the
temporary molding of the core in the die (FIG. 5F) . With the
upper punch exerting no compression on the temporary molding
of the core and the uncolored molding material A in the die,
the lower outer punch was raised manually until its punch tip
aligned with the lower center punch tip, so that the colored
temporary molding of the core was raised toward the upper
punch (FIG. 5G) with the rising of the lower outer punch to
form a space between the temporary molding of the core and the
lower center punch for the molding material A to be led into
the space (FIGs. 5G and 5H). Further, the upper punch and the
lower punch were moved toward each other and the manual
compression was performed to allow the uncolored molding
material A to be led with collapsing into thus space. In this
way, it was possible to manufacture a tablet with a core by
performing the supply of powder only twice. FIG. 51 shows a
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tablet with a core in a condition ready to be taken out.
Industrial Applicability
[0057]
The present invention can find wide application in
manufacturing a molding by compressing molding material
represented by powder granule, for example, in molding of
pharmaceuticals, foods, agricultural chemicals, sanitary
products, powder metallurgy-related products and the like, in
molding of semiconductor encapsulating resin for electronic
functional parts, and in molding of battery-related products
and the like.
[0058]
The manufacturing method of the present invention
can be practiced by using a rotary compression molding machine
comprising: dies mounted at a predetermined pitch on a
turntable rotatably mounted in a frame, the dies each having a
die bore; and upper and lower punches each having a double
structure according to the present invention which are
vertically slidably held on the upper and lower sides of each
die, wherein molding material supplied in each die is
compression-molded by pressing the upper and lower punches
inserted in the die bore of each die.
